I have a object Contact
public class Contact(){
private Integer idContact
private Date dateDebut;
private Date dateFin;
...............
public Contact(){}
// getters and setters
}
and List<Contact> contacts
I want to find the Object having the minimum of dateDebut and the Object having maximum of dateFin using Collections.sort(contacts) or other method.
Create an inline anonymous Comparator class and assign it to a constant:
public static final Comparator<Contact> DATE_DEBUT_COMPARATOR = new Comparator<Contact>() {
public int compare(Contact c1, Contact c2) {
return c1.dateDebut.compareTo(c2.dateDebut);
}
}
You can use java.util.Collections.sort(List<T>, Comparator<? super T>)
static Comparator<Contact> DATEDEBUT_COMPARATOR = new Comparator<Contact>() {
@Override
public int compare(Contact first, Contact second) {
assert(first != null);
assert(second != null);
return first.getDateDebut().compareTo(second.getDateDebut());
}
}
static Comparator<Contact> DATEFIN_COMPARATOR = new Comparator<Contact>() {
@Override
public int compare(Contact first, Contact second) {
assert(first != null);
assert(second != null);
return first.getDateFin().compareTo(second.getDateFin());
}
}
not null cause if they are you may encounter a NullPointerException at runtime.static Comparator<Contact> DATE_DEBUT_COMPARATOR = new Comparator<Contact>() {
@Override
public int compare(Contact first, Contact second) {
return first.getDateDebut().compareTo(second.getDateDebut());
}
// Ascending order of debut date
};
static Comparator<Contact> DATEFIN_COMPARATOR = new Comparator<Contact>() {
@Override
public int compare(Contact first, Contact second) {
return second.getDateFin().compareTo(first.getDateFin());
}
// Descending order of fin date
};
Passing comprator to Collections Util, can find object with min debut date at first location of Arraylist
Collections.sort(contactList, DATE_DEBUT_COMPARATOR);
Similarly passing comprator to Collections Util, can find object with max fin date at first location of Arraylist
Collections.sort(contactList, DATE_FIN_COMPARATOR);
Comparatorclass. It has little to do with theContactclass anyway.